1. Technical Field
The present invention relates to an object detection apparatus for detecting a target object from an input image by using an image recognition dictionary.
2. Related Art
A known object detection apparatus for detecting a target object that is an object to be detected, such as a person or a vehicle present forward or rearward of a subject vehicle, applies an image recognition algorithm using a recognition dictionary describing reference data for the target object to an image captured by and received from a camera or the like. For example, an object detection apparatus as disclosed in Japanese Patent Application Laid-Open Publication No. 2010-79716 recognizes the presence of a pedestrian by matching the captured image with template data (referred to as an image recognition dictionary) for detecting the pedestrian.
The image recognition dictionary used in the image recognition of the target object is predefined for a specific assumed environmental condition. However, if an environmental condition when the image was captured is far different from the environmental condition assumed when the image recognition dictionary was predefined, robustness of the image recognition results obtained by using the image recognition dictionary will be reduced and thus performance of detecting the target object will be lowered.
The environmental conditions that may cause variations in the detection performance includes, but are not limited to, sunshine conditions (brightness), weather conditions (precipitation), daytime and nighttime hours, backdrop attributes (an urban area, a suburban area, a mountain area etc.), and active and inactive states of lighting devices or wipers. Hence stable performance of detecting the target object may not be achieved even when the image recognition processing that uses the image recognition dictionary and the image recognition technique predefined for the specific assumed environmental condition is applied to the images captured in various changing environmental conditions ambient to the target object.
In consideration of the foregoing, it would therefore be desirable to have an object detection apparatus that is capable of reliably detecting a target object in an input image even in various changing environmental conditions ambient to the target object.